1. Field of the Invention
The present invention relates to a combination electrical hand-held tool, such as a combination hammer, with at least partial rotational movement of a working tool.
2. Description of the Prior Art
In combination electrical hand-held tools, one drive provides for both rotational and percussion movements, which permits switching, by using a manually actuatable mode selection switch connected with the drive, between different operational modes such as drilling, drilling and chiseling, and chiseling.
In one operational mode, e.g., chiseling, the transmission of a torque from a drive to working tool-receiving chuck is interrupted. As a result, the rotation of the chuck relative to the housing is prevented. The chuck, at that, usually can occupy more than one discrete angular positions relative to the housing.
U.S. Pat. No. 5,379,848 discloses a tool in which a rotatable mode selection switch provides for switching between pure rotational and pure percussion movements of a working tool. The switching is effected by an axial displacement of a switching sleeve which is associated with a percussion mechanism and surrounds a rotatable guide tubular member connected with a working tool-receiving chuck. An eccentric switching element, which engages the switching sleeve, connects the switching sleeve with the mode selection switch.
German Publication DE 42 06 840 A1 discloses a tool in which an axially displaceable switching sleeve is connected with a guide tubular member, which is connected with a working tool-receiving chuck, for joint rotation therewith. The switching sleeve is displaceable at least between two positions by associated toothing means. Toothing for blocking the rotational movement of the chuck is arranged in the tool housing without a possibility of rotation relative thereto.
In a tool disclosed in European publication EP-O 759 342 A2, in response to actuation of a rotatable mode selection switch, an axially displaceable, spring-biased blocking sleeve blocks rotation of a guide tubular member, which is connected with the chuck, relative to the tool housing. To this end, the blocking sleeve is provided with a radial circumferential toothing that cooperates with radial circumferential mating toothing provided on the guide tubular member.
In a tool disclosed in U.S. Pat. No. 4,763,733, an axially displaceable switching sleeve, which is provided with radial openings over its circumference, is mounted on a guide tubular member, which is connected with the tool chuck, and is connected with the guide tubular member for joint rotation therewith. The blocking of the rotational movement of the chuck relative to the housing is effected with a bolt which is supported in the housing without a possibility of rotation relative thereto and which radially engages, from outside, in the sleeve openings. The displacement of the bolt is effected in response to actuation of a rotatable mode selected switch.
An object of the present invention is to provide reliable means for blocking the rotational movement of a working tool-receiving chuck with respect to a housing of combination electrical hand-held tool.
This and other objects of the present invention which will become apparent hereinafter, are achieved by providing a combination electrical hand-held tool having a plurality of operational modes and including a housing, a tool spindle rotatably supported in the housing for rotation about a rotational axis, and an outer sleeve arranged coaxially with the tool spindle and connected thereto for joint rotation therewith. A bolt is supported in the housing without a possibility of rotation relative thereto and is displaceable in a direction transverse to the rotational axis for engaging in at least one opening provided in the sleeve at least in one of the operational modes of the electrical tool. A manually actuatable mode selection switch controls displacement of the bolt. A sliding sleeve, which is supported on a drive shaft of the electrical tool, is connected with the bolt for displacing the same in response to actuation of the mode selection switch.
According to the present invention, advantageously, the displacement of the sliding sleeve in effected with a switching element which engages in the sliding sleeve and is displaced manually via the mode selection switch.
In this way, the sleeve and the bolt engaging in the sleeve block the rotation of the tool chuck relative to the housing.
Advantageously, the outer sleeve surrounds the guide tube in which a percussion piston is displaceable for imparting a percussion movement to the tool chuck.
Advantageously, the outer sleeve is provided, at one of its opposite sides, with a bevel gear which is engageable with bevel drive pinion for effecting rotation of the sleeve. The drive pinion is secured on the drive shaft which advantageously extends transverse to the rotational axis of the chuck.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to is construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawings.